Heat exchangers with multi-layer structures

ABSTRACT

A heat exchanger includes a pair of opposed, spaced apart heat exchanger plates defining a heat exchanger volume therebetween having an inlet and opposed outlet. A plurality of heat exchanger ribs are included within the heat exchanger volume. Each rib defines a rib body spanning the heat exchanger volume. Each rib body includes a plurality of slits therethrough to define a flow path through the heat exchanger ribs from the inlet to the outlet of the heat exchanger volume. The ribs and slits can be formed using ultrasonic additive manufacturing (UAM), for example.

CROSS-REFERENCE TO RELATED APPLICATION

This Application is a Division of application Ser. No. 13/934,362 filedon Jul. 3, 2013. The entire contents of this application is incorporatedherein by reference in their entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to heat exchangers, and more particularlyto heat exchangers for liquid cooled motor controllers, for example.

2. Description of Related Art

Traditional cold plates used in liquid cooled motor controllers are madeby vacuum brazing processes. There are known issues with brazing ifprocess parameters are not well controlled. Examples include warpedsurfaces as well as melted and deformed fin cores. These result inhigher pressure drops and reduced thermal performance.

Such conventional methods and systems have generally been consideredsatisfactory for their intended purpose. However, there is still a needin the art for heat exchangers that allow for improved manufacturabilityand performance. There also remains a need in the art for such heatexchangers that are easy to make and use. The present disclosureprovides a solution for these problems.

SUMMARY OF THE INVENTION

A heat exchanger includes a pair of opposed, spaced apart heat exchangerplates defining a heat exchanger volume therebetween having an inlet andopposed outlet. A plurality of heat exchanger ribs are included withinthe heat exchanger volume. Each rib defines a rib body spanning the heatexchanger volume. Each rib body includes a plurality of slitstherethrough to define a flow path through the heat exchanger ribs fromthe inlet to the outlet of the heat exchanger volume.

In certain embodiments, each rib includes a plurality of additivemanufacturing layers aligned with a flow direction defined through theslits thereof. For example, each rib can include a plurality ofultrasonic additive manufacturing layers aligned with a flow directiondefined through the slits thereof.

In another aspect, each of the slits can be substantially rectangular.The slits in each rib can define a rectangular array of slits. Forexample, the rectangular array can include nine slits in a three bythree array, or twelve substantially rectangular slits longitudinallyaligned in a four by three array four slits wide along a directiondefined by long sides of the substantially rectangular slits. Each ribcan have a thickness in a flow direction defined through the slitsthereof, and the ribs can be spaced apart from one another in the flowdirection by a distance substantially equal to the rib thickness. Eachslit in each rib can aligned with a corresponding slit in each of theother ribs. It is also contemplated that each slit in each rib can beout of alignment with a corresponding slit in adjacent ribs.

A cold plate for a liquid cooled motor controller includes a cold platebody defining a plurality of cooling channels. A heat exchanger asdescribed above is defined in the cold plate body with the inlet of theheat exchanger in fluid communication with a first one of the coolingchannels and with the outlet of the heat exchanger in fluidcommunication with a second one of the cooling channels for cooling ofthe cold plate body by circulation of fluid through the cooling channelsand heat exchanger.

In certain embodiments, the heat exchanger is a first heat exchanger andthe cold plate further includes a second heat exchanger as describedabove defined in the cold plate body. A third one of the coolingchannels is in fluid communication with the outlet of the second heatexchanger, and the second cooling channel connects the outlet of thefirst heat exchanger in fluid communication and in series with the inletof the second heat exchanger.

It is also contemplated that the second heat exchanger can be connectedin parallel with the first heat exchanger. For example, the firstcooling channel can be in fluid communication with the inlets of bothheat exchangers in parallel, and the second cooling channel can be influid communication with the outlets of both heat exchangers inparallel.

A method of making a heat exchanger as described above includes formingthe plurality of heat exchanger ribs using additive manufacturing. Aplurality of layers are successively deposited, and in certainembodiments machined, to form the rib bodies and slits.

In certain embodiments, the method further includes mounting the heatexchanger to a cold plate for cooling a motor controller, i.e. the heatexchanger and cold plate are formed separately and then are joinedtogether. It is also contemplated that the method can include integrallyforming cold plate for cooling a motor controller wherein the cold plateand heat exchanger are integrally formed together in a single additivemanufacturing process.

These and other features of the systems and methods of the subjectinvention will become more readily apparent to those skilled in the artfrom the following detailed description of the preferred embodimentstaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosureappertains will readily understand how to make and use the devices andmethods of the subject disclosure without undue experimentation,preferred embodiments thereof will be described in detail herein belowwith reference to certain figures, wherein:

FIG. 1 is a perspective view of an exemplary embodiment of a heatexchanger constructed in accordance with the present disclosure, showingthe pair of opposed, spaced apart heat exchanger plates with a pluralityof heat exchanger ribs therebetween;

FIG. 2 is a partially cut away perspective view of the heat exchanger ofFIG. 1, showing the slits defined through the heat exchanger ribs;

FIG. 3 is a cross-sectional inlet end elevation view of a portion of theheat exchanger indicated in FIG. 2, showing the additive manufacturinglayers forming one of the ribs with slits therethrough;

FIG. 4 is a cross-sectional side elevation view of the heat exchanger ofFIG. 1, taken a the section line indicated in FIG. 1, showing the flowpath for cooling fluid through the slits of the heat exchanger ribs;

FIG. 5 is a perspective view of another exemplary embodiment of a heatexchanger, wherein the slits in each rib form a three by three array ofslits;

FIG. 6 is a perspective view of a portion of another exemplaryembodiment of a heat exchanger, wherein the slits are misaligned fromone rib to the next;

FIG. 7 is a schematic plan view of an exemplary embodiment of a coldplate including two heat exchangers such as that shown in FIG. 1connected in series with one another; and

FIG. 8 is a schematic plan view of an exemplary embodiment of a coldplate including two heat exchangers such as that shown in FIG. 1connected in parallel with one another.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectdisclosure. For purposes of explanation and illustration, and notlimitation, a partial view of an exemplary embodiment of a heatexchanger in accordance with the disclosure is shown in FIG. 1 and isdesignated generally by reference character 100. Other embodiments ofheat exchangers in accordance with the disclosure, or aspects thereof,are provided in FIGS. 2-8, as will be described. The systems and methodsdescribed herein can be used to provide cooling such as for motorcontrollers or the like. Heat exchanger 100 includes a pair of opposed,spaced apart heat exchanger plates 102 defining a heat exchanger volumetherebetween having an inlet 104 and opposed outlet 106. A plurality ofheat exchanger ribs are included within heat exchanger volume 104, eachrib defining a rib body 108 that spans the heat exchanger volumevertically and laterally in one direction as oriented in FIG. 1. In FIG.2, a portion of one of the heat exchanger plates 102 is shown removed toshow more of the rib bodies 108. While no side walls are shown in FIGS.1 and 2 for confining fluid to flow from inlet 104 to outlet 106, thoseskilled in the art will readily appreciate that side walls can be added,or can be formed as part of a cold plate body such as described below.

With reference now to FIG. 3, each rib body 108 includes a plurality ofslits 110 therethrough to define a flow path, indicated in FIG. 4,through the heat exchanger ribs from inlet 104 to outlet 106 of the heatexchanger volume. FIG. 3 shows one rib body 108 where the flow directionis into and out of the viewing plane. In FIG. 4, the flow path isindicated schematically by flow arrows, where the flow direction is leftto right. Flow enters inlet 104, passes through slits 110 in the firstrib body 108 into a first plenum 112, and then alternates betweensuccessive sets of slits 110 and plena 112 until flowing out from outlet106, which is not shown in FIG. 4, but see FIGS. 1 and 2.

Referring again to FIG. 3, each rib body 108 is made of a plurality ofadditive manufacturing layers 114. It should be noted that for sake ofclarity layers 114 are depicted schematically in FIG. 3, and that eachdepicted layer 114 can itself include several physical UAM depositedlayers. Each layer 114 is aligned with the flow direction definedthrough the slits 110 of the rib bodies 108, i.e., the flow directionindicated in FIG. 4. Layers 114 form vertical columns 116 between slits110, as well as forming the horizontal rungs 118 between the slits 110,as oriented in FIG. 3.

Layers 114 can be formed using ultrasonic additive manufacturing (UAM).In the UAM formation of rib bodies 108, a plurality of layers 114 aresuccessively deposited and optionally machined to form the rib bodiesand slits. For example, a few metal layers can be deposited on a firstheat exchanger plate, e.g., the lower heat exchanger plate 102 in FIG.3. These first few metal layers 114 form a first level of rungs 118 foreach of lower slits in each rib body 108 as oriented in FIG. 3. Plena112, as shown in FIG. 4, can be machined out of these first layers 114.The next few layers 114 are then deposited and slits 110 and plena 112are machined away from each layer 114. Then a few layers 114 aredeposited to form the next level of rungs 118, where the layers 114 aremachined to form plena 112, but are not machined for slits. This patterncan be continued until a final level of rungs is formed, e.g., the toplayers 114 of rib body 108 in FIG. 3. Then a final heat exchanger plate102 can be deposited onto the structure. Heat exchanger plates 102 canthemselves be formed of multiple UAM deposited layers 114, for example.It is also contemplated that each rib body 108 can be separately formedby additive manufacturing, then heat exchanger 100 can be formed byassembling all of the rib bodies 108 into place between plates 102. Inlieu of or in combination with machining successively deposited layers114, partial UAM layers can be used with slits and/or plena alreadyformed in the layers before deposition.

Each of the slits 110 is rectangular, and the slits 110 in each rib candefine a rectangular array of slits. For example, as shown in FIG. 2,the rectangular array includes twelve substantially rectangular slits110 longitudinally aligned in a four by three array that is four slitswide along the direction defined by the long sides of the slits 110. Forsake of clarity the individual slits 110 are not indicated in FIG. 2,but see FIGS. 3 and 4. It is also contemplated that any other suitablearray can be used, for example the heat exchanger 200 shown in FIG. 5has slits in a three by three array.

As indicated in FIG. 4, each rib body 108 has a thickness tin the flowdirection shown in FIG. 4, and the rib bodies 108 are spaced apart fromone another in the flow direction by a distance substantially equal tothe rib thickness t. In other words, each plenum 112 spans a gap thathas a thickness substantially equal to the rib thickness t. Thoseskilled in the art will readily appreciate that any other rib thicknessand spacing can be used as suitable for a given application withoutdeparting from the scope of this disclosure.

Each slit 110 in each rib body 108 is aligned with the correspondingslits 110 in each of the other rib bodies in heat exchanger 100. Thevertical aspect of this alignment can be seen in FIG. 4, where the upperslits 110 are aligned to one another, the middle slits 110 are alignedto one another, and the lower slits 110 are aligned to one another. Theslits 110 are also aligned in the horizontal direction, as shown in FIG.2. Those skilled in the art will readily appreciate that this slitalignment provides for low pressure drop with a high heat transfercoefficient. In applications where more pressure drop is acceptable,heat transfer can be further enhanced by misaligning the slits. Forexample, in FIG. 6 heat exchanger 300 is shown with one of the platesremoved to show the slits of successive ribs staggered relative to oneanother. This creates a flow path from each slit that impinges on thecolumn 316 between slits of the next rib in the flow path. It is alsocontemplated that the rungs between slits, e.g., rungs 118 shown in FIG.3, can similarly be out of alignment to enhance heat transfer forappropriate applications, i.e., the slits in successive ribs in the flowpath can be misaligned vertically and/or horizontally.

With reference now to FIG. 7, a cold plate 10 for a liquid cooled motorcontroller includes a cold plate body 12 defining a plurality of coolingchannels. A heat exchanger 100 as described above is defined in coldplate body 12 with inlet 104 of the heat exchanger in fluidcommunication with a first one of the cooling channels, i.e. channel 14,and with outlet 106 of heat exchanger 100 in fluid communication with asecond one of the cooling channels, i.e., channel 16 for cooling of coldplate body 12 by circulation of fluid through the cooling channels andheat exchanger 100. A second heat exchanger 100 as described above isalso defined in cold plate body 12 with a third one of the coolingchannels, i.e., channel 18, connected in fluid communication with outlet106 of the second heat exchanger 100. Channel 16 connects outlet 106 ofthe first heat exchanger 100 in fluid communication and in series withinlet 104 of the second heat exchanger 100. A connector 20, such as aquick disconnect, is included for connecting channels 14 and 18 of coldplate 10 to a supply for in flow and out flow of cooling fluid. It isalso contemplated that a parallel configuration can be used. Forexample, in the embodiment shown in FIG. 8, cold plate 50 includes asecond heat exchanger 100 connected in parallel with a first heatexchanger 100. The first cooling channel 54 is in fluid communicationwith the inlets 104 of both heat exchangers 100 in parallel, and secondcooling channel 56 is in fluid communication with the outlets 106 ofboth heat exchangers 100 in parallel. Those skilled in the art willreadily appreciate that any suitable number of heat exchangers 100 canbe included, including solitary heat exchanger configurations, in anycombination of series and/or parallel connections within a cold platewithout departing from the scope of this disclosure. While it iscontemplated that cold plates as described above can be used for coolingmotor controllers, those skilled in the art will readily appreciate thatcold plates and heat exchangers as disclosed herein can be used in anyother suitable application without departing from the scope of thisdisclosure. Complete heat exchangers, such as heat exchangers 100 madeby additive manufacturing as described above, can be mounted to a coldplate, e.g., cold plate 10. In other words, the heat exchangers and coldplate can be formed separately and then can be joined together. It isalso contemplated that the cold plate, including the channels, and heatexchanger or heat exchangers can be integrally formed together in asingle additive manufacturing process, wherein at least some of thelayers deposited as described above form portions of both the cold platebody and the heat exchanger or heat exchangers.

The methods and systems of the present disclosure, as described aboveand shown in the drawings, provide for heat exchangers with superiorproperties including improved performance and manufacturability. Whilethe apparatus and methods of the subject disclosure have been shown anddescribed with reference to preferred embodiments, those skilled in theart will readily appreciate that changes and/or modifications may bemade thereto without departing from the spirit and scope of the subjectdisclosure.

What is claimed is:
 1. A heat exchanger comprising: a pair of opposed,spaced apart heat exchanger plates defining a heat exchanger volumetherebetween having an inlet and opposed outlet; and a plurality of heatexchanger ribs within the heat exchanger volume, each rib defining a ribbody spanning the heat exchanger volume, each rib body including aplurality of slits therethrough to define a flow path through the heatexchanger ribs from the inlet to the outlet of the heat exchangervolume.
 2. A heat exchanger as recited in claim 1, wherein each ribincludes a plurality of additive manufacturing layers aligned with aflow direction defined through the slits thereof.
 3. A heat exchanger asrecited in claim 1, wherein each rib includes a plurality of ultrasonicadditive manufacturing layers aligned with a flow direction definedthrough the slits thereof.
 4. A heat exchanger as recited in claim 1,wherein each of the slits is substantially rectangular.
 5. A heatexchanger as recited in claim 1, wherein the slits in each rib define arectangular array of slits.
 6. A heat exchanger as recited in claim 5,wherein the rectangular array includes nine slits in a three by threearray.
 7. A heat exchanger as recited in claim 5, wherein therectangular array includes twelve substantially rectangular slitslongitudinally aligned in a four by three array four slits wide along adirection defined by long sides of the substantially rectangular slits.8. A heat exchanger as recited in claim 1, wherein each rib has athickness in a flow direction defined through the slits thereof, andwherein the ribs are spaced apart from one another in the flow directionby a distance substantially equal to the rib thickness.
 9. A heatexchanger as recited in claim 1, wherein each slit in each rib isaligned with a corresponding slit in each of the other ribs.
 10. A heatexchanger as recited in claim 1, wherein each slit in each rib is out ofalignment with a corresponding slit in adjacent ribs.
 11. A cold platefor a liquid cooled motor controller comprising: a cold plate bodydefining a plurality of cooling channels, wherein a heat exchanger asrecited in claim 1 is defined in the cold plate body with the inlet ofthe heat exchanger in fluid communication with a first one of thecooling channels and with the outlet of the heat exchanger in fluidcommunication with a second one of the cooling channels for cooling ofthe cold plate body by circulation of fluid through the cooling channelsand heat exchanger.
 12. A cold plate as recited in claim 11, wherein theheat exchanger is a first heat exchanger and further comprising a secondheat exchanger as recited in claim 1 defined in the cold plate body,with a third one of the cooling channels in fluid communication with theoutlet of the second heat exchanger, and with the second one of thecooling channels connecting the outlet of the first heat exchanger influid communication in series with the inlet of the second heatexchanger.
 13. A cold plate as recited in claim 12, wherein the heatexchanger is a first heat exchanger and further comprising a second heatexchanger as recited in claim 1 defined in the cold plate body, with thefirst one of the cooling channels in fluid communication with the inletsof both heat exchangers in parallel, and with the second one of thecooling channels in fluid communication with the outlets of both heatexchangers in parallel.
 14. A cold plate as recited in claim 11, whereineach of the slits is substantially rectangular.
 15. A cold plate asrecited in claim 11, wherein the slits in each rib body define arectangular array of slits.
 16. A cold plate as recited in claim 11,wherein each rib includes a plurality of ultrasonic additivemanufacturing layers aligned with a flow direction defined through theslits thereof.
 17. A cold plate as recited in claim 11, wherein eachslit in each rib is aligned with a corresponding slit in each of theother ribs.
 18. A method of making a heat exchanger as recited in claim1, the method comprising: forming the plurality of heat exchanger ribsusing additive manufacturing, wherein a plurality of layers aresuccessively deposited to form the rib bodies and slits.
 19. A method asrecited in claim 18, further comprising mounting the heat exchanger to acold plate for cooling a motor controller.
 20. A method as recited inclaim 18, wherein the step of forming includes forming a cold plate forcooling a motor controller wherein the cold plate and heat exchanger areintegrally formed together in a single additive manufacturing process.